Backstepping Based Sliding-mode Sensorless Control of Permanent Magnet Synchronous Motor

In order to solve the problem that permanent magnet synchronous motor (PMSM) can not be applied with sensors in a specific environment, considering the uncertainty of load torque, a sensorless sliding mode control of PMSM based on backstepping method is proposed. Firstly, by replacing the sign function with the sigmoid function, the high frequency buffeting caused by the traditional sliding mode observer is avoided. Secondly, the rotor speed and position are extracted by the PLL, the low-pass filter and phase compensation module are eliminated, and the sliding mode observer is designed. Then, considering the uncertain influence of load torque, a backstepping control algorithm was designed to control the PMSM, and its stability was proved by Lyapunov stability analysis. Finally, the simulation is carried out on Matlab/Simulink. The results show that the sensorless control algorithm can effectively estimate rotor speed and position, the system has good dynamic and static characteristics.